EVAL-AD5252EBZ Analog Devices Inc, EVAL-AD5252EBZ Datasheet - Page 18

• Manufacturer Part Number: EVAL-AD5252EBZ
• Description: EVALUATION BOARD
• Manufacturer: Analog Devices Inc

Specifications of EVAL-AD5252EBZ

• Main Purpose: Digital Potentiometer
• Utilized Ic / Part: AD5252
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD5251/AD5252
RDAC/EEMEM Quick Commands
The AD5251/AD5252 feature 12 quick commands that facilitate
easy manipulation of RDAC wiper settings and provide RDAC-
to-EEMEM storing and restoring functions. The command
format is shown in Figure 31, and the command descriptions
are shown in Table 9.
When using a quick command, issuing a third byte is not
needed, but is allowed. The quick commands reset and store
RDAC to EEMEM require acknowledge polling to determine
whether the command has finished executing.
R
The AD5251/AD5252 feature patented R
the nonvolatile memory. The tolerance of each channel is stored
in the memory during the factory production and can be read
by users at any time. The knowledge of the stored tolerance,
which is the average of R
users to predict R
precision, rheostat mode, and open-loop applications in which
knowledge of absolute resistance is critical.
The stored tolerances reside in the read-only memory and are
expressed as percentages. Each tolerance is stored in two memory
locations (see Table 10 ). The tolerance data is expressed in sign
magnitude binary format stored in two bytes; an example is shown
in Figure 32. For the first byte in Register N, the MSB is
designated for the sign (0 = + and 1 = –) and the 7 LSB is
designated for the integer portion of the tolerance. For the
second byte in Register N + 1, all eight data bits are designated
Table 9. RDAC-to-EEMEM Interface and RDAC Operation Quick Command Bits (CMD/ REG = 1, A2 = 0)
C3
0
0
0
0
0
0
0
0
1
1
1
1
1
:
:
1
1
This command leaves the device in the EEMEM read power state, which consumes power. Issue the NOP command to return the device to its idle state.
AB
Tolerance Stored in Read-Only Memory
C2
0
0
0
0
1
1
1
1
0
0
0
0
1
:
:
1
AB
accurately. This feature is valuable for
C1
0
0
1
1
0
0
1
1
0
0
1
1
0
:
:
1
AB
over all codes (see Figure 16), allows
0
1
0
1
0
1
1
0
1
0
1
C0
0
1
0
:
:
AB
tolerances storage in
Command Description
NOP
Restore EEMEM (A1, A0) to RDAC (A1, A0)
Store RDAC (A1, A0) to EEMEM (A1, A0)
Decrement RDAC (A1, A0) 6 dB
Decrement all RDACs 6 dB
Decrement RDAC (A1, A0) one step
Decrement all RDACs one step
Reset: restore EEMEMs to all RDACs
Increment RDACs (A1, A0) 6 dB
Increment all RDACs 6 dB
Increment RDACs (A1, A0) one step
Increment all RDACs one step
Reserved
:
:
Reserved
Rev. B | Page 18 of 28
for the decimal portion of tolerance. As shown in Table 10 and
Figure 32, for example, if the rated R
readback from Address 11000 shows 0001 1100 and
Address 11001 shows 0000 1111, then RDAC0 tolerance can be
calculated as
MSB: 0 = +
Next 7 MSB: 001 1100 = 28
8 LSB: 0000 1111 = 15 × 2
Tolerance = 28.06% and, therefore,
R
EEMEM Write-Acknowledge Polling
After each write operation to the EEMEM registers, an internal
write cycle begins. The I
determine if the internal write cycle is complete and the I
interface is enabled, interface polling can be executed. I
interface polling can be conducted by sending a start condition,
followed by the slave address and the write bit. If the I
interface responds with an ACK, the write cycle is complete and
the interface is ready to proceed with further operations. Other-
wise, I
Command 2 and Command 7 also require acknowledge polling.
EEMEM Write Protection
Setting the WP pin to logic low after EEMEM programming
protects the memory and RDAC registers from future write
operations. In this mode, the EEMEM and RDAC read
operations function as normal.
AB_ACTUAL
2
C interface polling can be repeated until it succeeds.
= 12.806 kΩ
1
2
C interface of the device is disabled. To
–8
= 0.06
AB
is 10 kΩ and the data
2
C
2
C
2
C